Inductive power coupling, as known in the art, allows energy to be transferred from a power supply to an electric load without connecting wires. A power supply is wired to a primary coil and an oscillating electric potential is applied across the primary coil, thereby inducing an oscillating magnetic field. The oscillating magnetic field may induce an oscillating electrical current in a secondary coil placed close to the primary coil. In this way, electrical energy may be transmitted from the primary coil to the secondary coil by electromagnetic induction without the two coils being conductively connected. When electrical energy is transferred from a primary coil to a secondary coil the coil pair are said to be inductively coupled. An electric load wired in series with such a secondary coil may draw energy from the power source wired to the primary coil when the secondary coil is inductively coupled thereto.
Induction type power outlets may be preferred to the more common conductive power sockets because they provide seamless power transmission and minimize the need for trailing wires.
The range of the inductive transmission as well as the strength of the induced voltage in the secondary inductor both vary according to the oscillating frequency of the electrical potential provided to the primary inductor. The induced voltage is strongest when the oscillating frequency equals the resonant frequency of the system. The resonant frequency fR depends upon the inductance L and the capacitance C of the system according to the equation:
      f    R    =            1              2        ⁢                                  ⁢        π        ⁢                  LC                      .  
Efficiency of energy transfer depends upon a number of parameters including the resonant frequency of the system, the transmission frequency of operation as well as the distance and alignment between the primary and secondary inductive coils. There is a need for an inductive power transmission system which is able to adapt to changing conditions and to transmit power at a wide range of intercoil distances. The embodiments described herein address this need.